Question

explain the principle of fiber optic cable. derive an expression for acceptance angle and numerical aperture​

Answer 1

Answer:

The refractive index of the core is ƞ1 and that of cladding is ƞ2. The figure below shows an optical fiber inside which light ray is focused. So, the ray XA is launched from denser medium to rarer medium by making an angle α with the fiber axis. This angle α is known as the acceptance angle of the fiber.